The negative priming task is widely used to investigate attentional inhibition. A critical review of the negative priming literature considers various parameters of the task (e.g., time course, relation to interference, level of occurence, and susceptibility to changes in task context). It takes into account life span data and the performance of patients diagnosed with schizophrenia. On these bases, the review suggests that negative priming can be produced by 2 mechanisms: memorial and inhibitory. With respect to inhibition, the review suggests that (a) there are 2 systems, one responsible for identity and the other for location information; and (b) inhibition is a flexible, postselection process operating to prevent recently rejected information from quickly regaining access to effectors, thus helping to establish coherence among selected thought and action streams.

The authors investigated the possibility that working memory span tasks are influenced by interference and that interference contributes to the correlation between span and other measures. Younger and older adults received the span task either in the standard format or one designed to reduce the impact of interference with no impact on capacity demands. Participants then read and recalled a short prose passage. Reducing the amount of interference in the span task raised span scores, replicating previous results (C. P. May, L. Hasher, & M. J. Kane, 1999). The same interference-reducing manipulations that raised span substantially altered the relation between span and prose recall. These results suggest that span is influenced by interference, that age differences in span may be due to differences in the ability to overcome interference rather than to differences in capacity, and that interference plays an important role in the relation between span and other tasks.

In two experiments, we investigated the possibility that susceptibility to proactive interference (PI) affects performance on memory span measures. Wetested both younger and older adults (older adults were tested because of the suggestion that they are differentially susceptible to PI). We used two different span measures and manipulated testing procedures to reduce PI for these tasks. For older adults, span estimates increased with each PI-reducing manipulation; for younger adults, scores increased when multiple PI manipulations were combined or when PI-reducing manipulations were used in paradigms in which within-task PI was especially high. The findings suggest that PI critically influences span performance. Weconsider the possibility that interference-proneness may influence cognitive behaviors previously thought to be governed by capacity.

Two experiments explore whether synchrony between peak circadian arousal periods and time of testing influences inhibitory efficiency for younger and older adults. Experiment 1 assesses inhibitory control over no-longer-relevant thoughts, and Experiment 2 assesses control over unwanted but strong responses, as well as performance on neuropsychological tasks that index frontal function. Inhibitory control is greatest at optimal times for both age groups and is generally greater for younger than for older adults. Performance on 2 neuropsychological measures (Stroop and Trails) also changes over the day, at least for older adults, and is correlated with inhibitory indexes, suggesting that for older adults changes in inhibition may be mediated by circadian variations in frontal functioning. By contrast, access to well-learned responses is not vulnerable to synchrony or age effects.

Three experiments examined whether negative priming is a dually determined effect produced by inhibitory mechanisms and by a memorial process. Younger adults (Experiment 1) and older adults (Experiments 1-3) were tested in procedures that varied the likelihood of inducing retrieval of the prior trial. This was done by making test-trial target decoding difficult (Experiments 1 & 2) or by making prior information useful on some nonnegative priming trials (Experiment 3). Younger adults demonstrated negative priming under retrieval and nonretrieval conditions, with patterns of performance indicating different sources of negative priming effects. Older adults showed negative priming only under retrieval-inducing conditions, consistent with the view of deficient inhibitory mechanisms for older adults. The data suggest that contextual variables critically determine whether negative priming is largely due to inhibition or to episodic retrieval.As evidenced by two recent volumes dedicated entirely to inhibitory theories of attention, memory, and language (Dagenbach & Carr, 1994a;Dempster & Brainerd, 1995), the role of inhibition in cognitive functioning is a current focus of investigation in mainstream psychology. Indeed, inhibitory mechanisms are now a prominent explanatory construct in a number of cognitive domains, including selective attention (e.g